'One'.relative_identifier(
  'Two',
  key: 'Three'
)
'One'.relative_identifier(
  'Two',
  key: 'Three'
)(
  'Four',
  key: 'Five'
)
'One'.relative_identifier key: 'Two'
'One'.relative_identifier unqualified 'Two',
                                      key: 'Three'
'One'.relative_identifier 'Two',
                          key: 'Three'